We propose to develop a new high atomic number (Z) solid state pixel detector for image acquisition in digital mammography. These detectors directly convert x-ray energy into electron-hole pairs and can provide superior spatial resolution, noise and radiation efficiency characteristics compared to both screen-film mammography detectors and digital detectors that are based on phosphor-fiber-optic-CCD technology. The detectors are expected to have high sensitivity and excellent x-ray quantum efficiency approaching 95% for 20 to 35 keV x-rays. The MTF and especially the DQE are expected to be markedly improved, because spreading of light that occurs in phosphor detectors is eliminated. Because of the high DQE of the detector and the use of a slot scanning geometry (no grid is necessary) the radiation dose may be significantly-reduced. The sensors are compact and lightweight and can, therefore easily be mounted on a scanning gantry. The major difference to other digital mammography systems is the superior performance high Z detector and the low noise readout electronics. The improved image quality and contrast is expected to result in significant improvement in both sensitivity and specificity of detection of breast cancer, particularly in women with dense breasts and will enhance the early detection of breast cancer. PROPOSED COMMERCIAL APPLICATIONS: The most important commercial application for the proposed research is digital mammography. It may lead to the development and manufacture of high contrast and low dose second generation digital mammography systems. The proposed sensor arrays may also be used for other radiography applications. These detectors are directly applicable to high resolution industrial nondestructive inspection, such as realtime product monitoring in factories and high resolution imaging of critical machinery components.